Heretofore, there is known a toothbrush in which the bending angle of a neck portion relative to a handle portion can be adjusted so that the most inner teeth, which are difficult to brush, such as molar teeth, are not left unbrushed. For example, Japanese Utility Model Laid-Open Application No. 63-13025 discloses a toothbrush in which a handle portion and a neck portion are pivotally supported by a pin and a screw is tightened relative to the pin at a predetermined angle.
Also, Japanese Utility Model Laid-Open Application No. 61-199231 discloses a toothbrush, in which the bending angle of a neck portion relative to a handle portion can be adjusted by sliding a control stick in the forward and backward direction of the handle portion.
However, in the toothbrush described in the above Japanese Utility Model Laid-Open Application No. 63-13025, both hands are required for adjusting the bending angle of the neck portion relative to the handle portion. Also, after the completion of the adjustment of angle, the toothbrush is used, with the neck portion fixedly maintained at that adjusted angle. Therefore, there is such an inconvenience that during the use of the toothbrush, the bending angle of the neck portion relative to the handle portion can not be easily adjusted depending on which tooth or which part of a tooth is to be brushed.
In the toothbrush disclosed in Japanese Utility Model Laid-Open Application No. 61-199231, it is constructionally very difficult to slide the control stick by a desired amount by a single hand during the use of the toothbrush. Moreover, it is constructionally practically impossible to change the bending angle of the neck portion relative to the handle portion in accordance with the sliding amount of the control stick.